Automated systems for storing tapes in a storage location and moving the tapes between the storage location and a tape drive are known in the prior art. Most of these prior art storage systems are designed to store and handle tapes containing audio and video data, such as television programs and commercials, which are housed in a single storage assembly. Associated with the storage assembly is at least one and preferably a plurality of tape drives, each of which is adapted to receive and play at least one of the tapes held in the storage assembly. While the tapes could be manually moved between the storage assembly and the tape drives, it is expedient to have a computer-controlled device which can be pre-programmed to select a tape, remove it from the storage assembly, transport it to the tape drive, insert the tape into the tape drive and, upon completion of play, remove the tape from the tape drive and return it to the storage assembly.
Some prior art systems use a circular storage configuration for storing the tapes. For example, U.S. Pat. No. 4,846,619 entitled "Robotic Materials Handling System", and issued Jul. 11, 1989 to Crabtree, et al., discloses a system for storing and handling box-like articles such as video cassettes. The system includes a storage area containing a plurality of columns of storage bins which are configured around the inside of a cylindrical storage area. A vertical shaft extends through the center of the cylindrical storage area and includes a manipulator assembly that is carried on the shaft. The manipulator assembly further includes a plurality of gripper mechanisms which may be positioned to load and unload the video cassettes from the storage bins.
U.S. Pat. No. 4,271,440 entitled "Automatic Tape Cartridge Handling System", issued Jun. 2, 1981 to Jenkins, et al., discloses a microcomputer-controlled tape cartridge handling system. The system includes two storage drums in a cylindrical configuration with 512 cartridge storage compartments arranged in 16 vertical columns around the circumference of the drum. Two tape cartridge transfer mechanisms are located adjacent to the two storage drums. The tape cartridge transfer mechanisms may be positioned to remove tape cartridges from either of the two storage drums.
Another storage system is disclosed in U.S. Pat. No. No. 3,938,190 entitled "Storage and Retrieval System for Magnetic Tape Cassettes", and issued Feb. 10, 1976 to Semmlow et al. This patent discloses a system for storing and retrieving information-bearing modules such as magnetic tape cassettes. The system includes a fixed two-dimensional storage array, a fixed processing or play station for extracting information from the information-bearing modules, and a movable selection mechanism having three degrees of freedom. This system is designed to provide simple and inexpensive access to a large store of audio or video cassettes. The system can also be used with compact disks, phonograph records, microfilm, microfiche, photographic slides, film cassettes, or non-informational items such as stock selection from a warehouse.
Despite the existence of these prior art storage and retrieval systems, there is a need for a mechanism for transporting data cartridges in an automated fashion between two or more storage assemblies in order to increase the available storage capacity and processing capability of the system (e.g. to run a number of data cartridges which are stored in the same storage assembly which is greater than the number of drives associated with that storage assembly).